How do you solder pipework which is at the lowest point of the circuit?

[PoP]

That was the problem facing me earlier today. Needed to replace a 15mm pipe coming off a tee. Problem was that it was below the lowest drain point on the water circuit, so I knew the pipe had water in it that would most likely cause problems when applying a blowtorch.

Solved the problem after sleeping on it overnight. I'm passing the following on in case it might be useful to someone else one of these days.

I drained the pipework as far as I could, leaving a few feet of 15mm containing water - with the tee midway along.

Then connected up my Acquvac vacuum cleaner configured in wet mode, stuck the hose on the tap on the end of the circuit, opened the tap at the other end of the pipework, and sucked the water out.

Within a couple of minutes I had nearly-dry pipework which allowed me to break and remake the 15mm solder tee without problems.

I suppose a complete job would have seen me put a drain valve on this pipework for good measure. Didn't bother - now that I know my trusty Aquavac can do the business I don't need the drain valve :)

PoP

[BigWallop]

Opening a tap and blowing through it, can do the same job, and it saves all the hassle of buying an aquavac.

[PoP]

Tried that. Unfortunately it didn't work too well :)

PoP

[Rick Hughes]

The 'Pro' answer would be to use a pipe freezer kit .... these will hold back water up stream, the soldering will boil it off where you are working.

Rick

[PoP]

Possibly. Only there was a problem with taking that approach. The tee was about centrally placed in the pipework - and on one side the pipe disappeared through a hole in the brickwork, without there being any access to the remote side. And the distance between the tee and the wall would have made the freeze too close to the flamethrower.

PoP

[Alex]

If you were replacing the pipe why not just cut the pipe and drain water into towel , bucket or something similar

[PoP]

I was replacing just one section of the tee - the pipe that branches off - the straight through pipe was being left in-situ.

I did think about replacing the tee and pipework, but unfortunately the main feed coming in (which is the bit I would have had to cut) had only a couple of inches before it disappeared into the brickwork, and being low down gave no room to be able to swing a hacksaw. Couldn't possibly get a pipe cutter in the space available so it was do-or-die with the 15mm tee.

PoP

[Thomas Prufer]

There's another trick for situations like this, I picked up here in uk.d-i-y AFAIK: Shove a bit of bread in the pipe. This is supposed to seal the pipe and soak up any water for long enough to solder the joint, and the dissolve as you flush the system. Never tried it...

Thomas Prufer

[David]

Never tried it myself, but allegedly this can also be solved by stuffing the open end of the pipe with bread; you then have until the bread plug becomes saturated to complete your soldering. When you turn the water on again, the bread disintegrates and comes out the tap or next junction in the pipework.

David

[PoP]

Whilst I can see the bread trick could work, it wouldn't have done for me. Reason being that there was something like an 18in head of water above the tee which I wanted to unsolder - that would be a lot of bread, and no way could I get this down past the tee anyway.

Sucking the water out with an Aquavac did the business on this occasion. I think I got about a pint and a half out of the pipe using that trick.

PoP

[Simon Avery]

Hello PoP

Or the Faq still has the "Bread trick", I think?

[Phil Addison]

The simple solution is to bung the vent and feed pipes in the attic, or wherever (see elsewhere for details) and cut the pipe, catching the 1/2 pint or so that flows out into a container. An automatic pipe cutter will cut a pipe within an inch of a parallel wall, and is less that a tenner. You then might need a straight coupler to repair the cut pipe - less than 75p.

-- Phil Addison The uk.d-i-y FAQ is at

NOSPAM from address to reply

[Thomas Prufer]

It's still a good trick. I've used an injector pump to do the same thing. (Or whatever they're called: one of those things that attaches to a mains water outlet and sucks when you turn on the water. Jet of water entrains the air, and "pulls" it out). Found in waterbed stores, nonelectric, cheap, fine dirt and sludge don't bother it.

It'll also pull a lot more head than a wet-n-dry, so beware crushing something.

Thomas Prufer